Sheet metal link and chain made thereof



m 1955 w. BISCHOFF 2,723,190

SHEET METAL LINK AND CHAIN MADE THEREOF Filed March 8, 1955 (V/22% Edw IG-M E? is gyfi 3 the inherent resilience of the comparatively thinmaterial of which the link is composed, render the wedging ele-' ments13 of all the combined links capable of performing the dual functions ofautomatically increasing the stillness of the chain when it is bentbeyond a certain degree of curvature and of locking the respective linksin assembled engagement with adjoining links. The precise manner inwhich these useful functions are performed will now be described.

The mode of link assembly in making up the chain in its squarecross-section form should be understood by referring to Fig. 4 inparticular. Assuming that the two links shown edgewise in that figurenext to the two broken links at the right end of the chain section arethe first links in a new chain, these two edgewise links are held inclosely abutting relation instead of angularly arranged as shown. Then,one other link is turned at right angles to the two first-mentionedlinks and is hooked through registering side slots 12 at one side of themedial slots 11 of said two links, which operation will bring the endsof the corresponding arms of the latter into medial slot 11 of the saidother, or third-mentioned, link. In doing this, the upturned wedgingelement 13 of the third-mentioned link will not pass freely through theside slots 12 of the first-mentioned links, because the verticalprojection of said upturned wedging element exceeds the width of eachside slot 12. It is necessary, therefore, to squeeze the front edgeportion of the third-mentioned link between the jaws of a pair oftweezers, or pliers, and thereby partially flatten the link until thevertical projection of wedging element 13 is reduced so that it willpass through slot 12. In assembling a fine chain, a holding tool, suchas tweezersor pliers, is required to pick up and manipulate each link,so it is the practice to engage the front portion of each link at theangle between its body 10 and wedging element 13 by the jaws of thesame, so the application of sufiicient pressure for securely grippingthe link will serve to flatten out the angle of upturn enough to permitsaid wedging element to clear the edges of side slot 12. After thethird-mentioned link has been threaded through the sideslots 12-12 ofboth first-mentioned links and the holding tool has been disengaged withthe former, it will spring back into its original form and wedgingelement- 13 thereof will become locked automatically againstdisengagement with the two first-mentioned links. Re-use of the holdingtool will be required thereafter to disassemble any link from lockedengagement with other adjoining links in the chain.

After the third-mentioned link has been assembled in interlockingengagement with the two first-mentioned links, a fourth link is pairedup with said third-mentioned link by threading it through the remainingunoccupied and registering side slots 12.12 in said two first-mentionedlinks, and in the same way with the aid of a holding tool. until thedesired length of chain is completed. As each pair of additional linksbecome assembled, it is the practiceto rotate the chain through an angleof ninety degrees to facilitate assembly of the succeeding pair oflinks.

The manner in which the wedging elements 13 automatically stiffen thechain when flexed laterally to a degree exceeding that of normal use ina large radius articlepof jewelry, such a necklace, will be understood upon particular reference to Fig. 6. For instance, supposingthat theupper and lower links of the pair represented in full lines becomeoscillated during lateral flexion ofthe chain on a vertical axis, thewedging elements of said links will become frictionally engaged with theabut tingedges-of the respective side slots 1212 in one of the rightandleft pair of links shown in cross-section dependingupon the direction offiexion. The result will be progressively increased frictionalresistance to fiexion as the wedging elements become more deeply wedgedinto the side slots. Upon restoration of the chain to a more Thereafter,the process is repeated as described nearly straight condition,frictional resistance will be relieved and the chain will become fullyflexible again.

In order to convert the originally square chain C shown in Figs. 4 to 6into a chain of pleasingly round cross-section, such as that shown inFig. 7, the square chain is inserted between the forming dies 1414 whichhave semi-cylindrical opposed faces of appropriate diameter, while beingheld with the diagonals of its square crosssectional form at an angle offorty-five degrees to the direction of movement of the dies. When thedies 1414 are then closed on each other, they will press the chain intoround form as at C, in which action the links of the chain becomedeformed without detracting from the ornamental appearance of the chainas a whole.

Dies 15-15 having semi-elliptical faces are employed to convert a squarechain C into a chain of elliptical cross- .section as at C". Before thedies are closed, the square chain C must be held with one diagonal inalignment with the direction of die movement.

It is to be understood that the present disclosure of the invention isan illustrative example and that various changes, modifications andalterations may be made in these structural embodiments which do notconstitute departures from the spirit and scope of the invention.

I claim:

1. As an article of manufacture, a chain link comprising a substantiallyC-shaped body having a stern and parallel arms with a medial slottherebetween which is open at its end opposite to said stem, and asubstantially triangular wedging element projecting from the stern ofthe body opposite to said medial slot with. its nose facing away fromthe latter, the arms of the body being provided with closed side slotsarranged substantially parallel to said medial slot and being slightlygreater in length than the distance between the nose of the wedgingelement and the inner end of said medial slot. i

2. As an article of manufacture, the chain link defined in claim 1,wherein the body is curved in the direction of the arms and slots.

3. As an article of manufacture, the chain link defined in claim 2,wherein the wedging element is bent oppositely with respect to theconcave side of the curvature of the link body.

4. As an article of manufacture, the chain link defined in claim 3,wherein the body is made of thin resilient material and the projectionof the wedging element angularly from the chord of curvature of the bodyexceeds the width of each side slot.

5. As an article of manufacture, the chain link defined in claim 1,wherein the body is made of thin resilient material and the projectionof the wedging element angularly from the chord of curvature of the bodyexceeds the width of each side slot.

6. As an article of manufacture, the chain link defined in claim 1,wherein the medial slot is at least twice as wide as each side slot. I

7. An auto-stiffening chain comprising plural interengaged links ofidentical structure, each link including a substantially C-shaped bodyhaving a stem and parallel arms with a medial slot therebetween which isopen at its end opposite to said stem and a substantially triangularwedging element projecting from the stem of the body opposite to saidmedial slot with its nose facing away from the latter, the arms of thebody being provided with closed side slots arranged substantiallyparallel to said medial slot and being slightly greater in length thanthe distance between the nose of the wedging element'and the inner endof said medial slot, in the interengaged rela tion of the severalcomponent links of the chain the latter being arranged in side-by-sidepairs with the links of each pair rotated aboutthe chain axissubstantially ninety degrees relative to the links of the nextsucceeding pair and having the arms of each link of any pair threadedthrough the registering side slots in corresponding arms of links of anadjoining pair, whereby the arms of both links of each pair areabuttingly confined in the registering wherein the body of each link iscurved longitudinally medial slots of the adjoining pair of links, thechain thus with the convex surface facing in the same direction as theproduced being substantially square in cross-section. angular bend inthe wedging element.

8. An auto-stiffening chain as defined in claim 7, wherein each link ismade from thin resilient material 5 Reffilwces Cited in the file Of thisPatent and the wedging element of each link is bent angularly UNITEDSTATES PATENTS with respect to the link body to such a degree that theprojection of said element away from the body is greater g g than thewidth of each side slot in the body arms. 2 169265 Magmz A 1939 9. Anauto-stifiening chain as defined in claim 8, 10

